Locking safety pin



Oct. 7, 1958 H. BURBIG 2,854,720

LOCKING SAFETY PIN I Filed Dec. 8. 1953 IN V EN TOR.

Han/av June/a BY M M {M United States Patent'O LOCKING SAFETY PIN HenryBurbig, New York, N. Y.

Application December 8, 1953, Serial No. 396,965

3 Claims. (Cl. 24-156) This invention relates to a locking type ofsafety pin.

Among the objects of this invention is to provide a safety pin with alocking means which is effective to prevent accidental opening of thepin.

Among other objects of the invention is to provide a safety pin having aflexible locking means mounted thereon which can be easily moved tolocking position but which will not be accidentally dislodged to permitopening of the pin.

These and other objects ancillary thereto are obtained by providing asafety pin of an ordinary type which has a head including a keeper meansat one end with a flexible elastic sleeve which is slidable along orabout the head and into a relatively fixed position on the keeper meansso that the said sleeve surrounds the region on the keeper whichreleasably holds the pointed prong. The head of such safety pinscomprises an oval opening and the inside of the elastic sleeve isadapted to slide or move about said opening into a position adjacent thetop or back part of the head whereupon the pointed prong can be insertedor removed from the keeper or into a position surrounding a substantialportion of the keeper and the inserted prong so that the said pointed orinserted prong cannot be removed without first moving said sleeve.

The sleeve is made of elastic plastic material so that it stretches toslide along the edge of the head. In most pins the very end of the ovalslot in the head is curved so that a sleeve of proper length is in anunstable position at the very' end thereof but flattened regions arepresent parallel to the prongs and keeper so that a properlyproportioned sleeve snaps into place at either side of the head.Suitable samples of elastic plastic material for the sleeve includepolyvinyl resins, polyethylene, nylon, various synthetic rubbers,plasticized cellulose derivatives such as cellulose acetate andcellulose acetate butyrate, etc. Materials which show at least a smallamount of elastic memory such as the vinyl resins have the additionaladvantage of tightening themselves in locking position after a lapse oftime. It is essential that the said sleeve be elastic and of greaterflexibility than the metal of which said pin is made.

The invention both a; to its organization and its method of operationtogether with additional objects and advantages thereof will best beunderstood from the following description of specific embodimentsthereof when read in connection with the accompanying drawing in which:

Fig. l is a plan view of the pin with the locking means in lockedposition.

Fig. 2 is a cross-sectional view taken on line 2 of Fig. 1.

Fig. 3 is a view similar to Fig. 1 but showing the-head of the pin incross section.

Fig. 4 is a view of the pin in unlocked and open position.

Fig. 5 is a detail view of a typical locking means.

The pin comprises the loop end 11, the stationary, back rod 12, thepointed prong 13 with end point 14, and the head 20.

w 2,854,720 Patented Oct, 7, 195.8

The head 20 is fixedly held on the curved end 15- of the back rod 12.The head is fixed to the end 15- by being clinched tightly about the end15 adjacent regions 21, 22. The portion of the head 20 which is spacedfrom end 15 expands to provide the keeper 23.. The interior portion ofthe head comprises slightly elongated oval shaped slots. This slotgenerally follows the outside contour of'the head but tends to closetoward the loop end of the pin. More specifically the slot is generallyrounded at the end 25 but has a surface region 26 about a portion of thekeeper 23 which is of reduced curvature or even partially flattened.Pins of this type are well known in the art and are manufacturedcommercially and one advantage of this invention is that the safety orlocking element can be combined with an already existing pin.

The locking element 30 is made of relatively flexible plastic materialand comprises a ring or sleeve with relatively thick walls which isadapted to fit tightly about a slotted portion of the head 20. Thelength of the sleeve 30 is approximately equal to or greater than thediameter of the slot 24 at its longest diameter. Under these conditions,the sleeve 30 is always under a slight tension. The position of leaststrain on the sleeve 30 is that shown in Fig. 4. As the sleeve is pushedaround slot 24, in the region of the curved area 25 the sleeve istensioned due to the forced curving of its axis by the shorter diameterof the slot. As the sleeve 20 is pushed into the locking position ofFigs. 1-3 the axis of the sleeve is straightened but the sleeve isexpanded due to the greater volume embraced by the keeper 23.Nevertheless, the sleeve snaps into locking position due apparently tothe flat surfaces on the outside of the keeper, the flat surface 26 andthe positioning of the end of cylinder 30 against the corner wherecurved surface 25 meets flattened surface 26.

Since the sleeve is slightly expanded when pushed into locking position,the elastic memory of the sleeve operates to tighten the grip thereofabout the keeper 23.

The sleeve may be expanded and slipped or forced onto the head of thepin over the keeper portion 23 of the head. If desired the keeperportion may first be sprung slightly out of place to permit the sleeve30 to be forced thereover and thereafter be forced back into position.

The features and principles underlying the invention described above inconnection with specific exemplifications will suggest to those skilledin the art many other modifications thereof. It is accordingly desiredthat the appended claims shall not be limited to any specific feature ordetails thereof.

I claim:

1. A locking safety pin comprising a safety pin having a back rod, apointed prong and a flat head with a rounded external end surface havinga thickness slightly greater than the thickness of the back rod attachedat one side thereof to the back rod and extending laterally toward saidpointed prong which head includes a keeper portion opposite said backrod adapted to releasably hold the pointed prong, the said head portionhaving an internal rounded slot which generally follows the outsidecontour of the head but includes a region of reduced curvature adjacentthe pointed prong holding part of the keeper portion, in combinationwith a locking means consisting essentially of a flexible plastic sleeveelastically fitting about the said head so as to slide around the same.

2. The locking safety pin as set forth in claim 1 in which the plasticsleeve is approximately as long as the width of the slot measuredtransversely of said head portion.

3. In combination, a locking safety pin comprising a safety pin of thetype comprising a back rod, a pointed r r 3 prong connected to the backrod by a spring element and a head including a hollow keeper portionsecured at one side to the free end of said back rod and extendingtoward said pointed prong, the said head including at least one roundedslot opening in the central region thereof adapted to admit the pointedend of said prong to the hollow keeper portion of the head, said roundedslot including a relatively straight edge portion paralleling theoutside of the keeper portion of the head and a locking means consistingessentially of a flexible plastic sleeve of smaller length than thelength of said slot and elastically fitting over the region of said headbetween the slot and the outside surface of the head so as to enclose atleast a portion of the slotted region, said plastic sleeve beingslidable around the slot and being under reduced tension 15 whensurrounding the relatively straight edge portion of said slot therebybeing adapted to lock the pointed prong in closed position.

References Cited in the file of this patent UNITED STATES PATENTS355,535 Jenkins Jan. 4, 1887 360,276 Carpenter Mar. 29, 1887 719,919Washburn Feb. 3, 1903 1,108,786 Pyron Aug. 25, 1914 2,246,495 AlessiJune 24, 1941 FOREIGN PATENTS 412,145 France 1910

